Many of the thousands of tourists who crowd Yellowstone National Park each year come to see the black bears that panhandle along the roadsides. This summer a number of the bears are missing in action. Around some campfires, a dark conspiracy theory grew. Park rangers, said the rumor, were shooting down the bears because 1) the bears cause traffic jams, or 2) so many visitors bitten by the bears have been suing the National Park Service for damages—and winning.
But there is a happier explanation. Since last year, the rangers have issued dozens of summonses and warnings to tourists who tried to...